Comments, observations and thoughts from two left coast bloggers on applied statistics, higher education and epidemiology. Joseph is a new assistant professor. Mark is a marketing statistician and former math teacher.

Wednesday, June 15, 2011

Americans are living longer, but not in every corner of the country. A new study shows that in hundreds of U.S. counties — mostly in the South — life expectancy has fallen.

The researchers believe problems like smoking and obesity are partly to blame.

"There are enormous variations within the country" said Dr. Christopher Murray, a University of Washington researcher. He's a study author and an editor of the online journal, Population Health Metrics, which released the study Wednesday.

Overall, life expectancy in the U.S. is at an all-time high. The Centers for Disease Control and Prevention recently estimated that a baby born in 2009 could expect to live 78 years and 2 months.

The CDC doesn't calculate estimates by county; Murray's research covers 2000 through 2007 when U.S. life expectancy grew a year to nearly 78.

A federal expert in these kinds of statistics said Murray's methods were sound, but the findings aren't terribly surprising.

The U.S. estimate actually dropped from 2004 to 2005, noted Bob Anderson of the CDC's National Center for Health Statistics. Given that downward blip — and the fact that statistics fluctuate more when you're dealing with smaller populations __ it's not unexpected to see some declines at the local level, he said.

The study found that life expectancy for women fell significantly in 702 of the nation's more than 3,100 counties. The largest declines — by nearly 2 years — were in Mississippi's Madison County, near Jackson, and the adjacent Hughes and Okfuskee counties in eastern Oklahoma.